If the
accent is an indicator for how a word should be pronounced
it is a so-called diacritical mark. In Spanish the accent
can also be a sign of grammatical function that is not
at all related to the pronunciation of the word. Then
the accent is a no diacritical mark.

For example it can be helpful
to get a hint whether it is a person he (él)
or an article (el). Interrogative pronouns always have
an accent (¿Cómo? ¿Cuándo?
¿Qué?).